Addition materials for iron and steel manufacture and method of use thereof



Patented May 19, 1 953 2,639,222 ADDITION MATERIALS FOR mosh-AND STEEL MANUFACTURE AND F USE THEREOF James views, oanron on e, ass-ignoiw enie meanness-emanation,canton, Oli-io, a eerpor'a'tioniof Ohio" Nomrat'ving.

"METHOD Aliiilicatiohoctober 19, 19 51, Serial No. 252,210

'14 Claims. (oi. fie-4305) This invention relates to amfadditioh material and a method of using it in molten ironand stem and more particularly relateste a material and method for making chromium additions to molden steel;

In the manufacture of chromium-containing ironior steel it is -the general-practice-to add the chromium tenithe moltenbath in the ,-fu-rna'ce in the;form.of-:ferrowhremiumr 'Dhe .:most-eom-mon form of ferroachnomiumz presently used isthat known as standard high carbon ferroschrome wh-ieh-oeontainsq about 65%;;120 7,01% fehromium, 41% to: l %tcarbon and a'bout maximum sillcon; In the: manufacture-ref chromium steels 1 in open hearth-furnaces, th usualrprocedureais to work-the carbon content i-ofthe' moltensteel "b ath down to the desired point then to block or ki-ll the. heat of =steel andvfinaliynto add the term-chromium; If: the: chromium :eontent of the steel isover it is frequently the-pram title to heat the term-chromium; before adding it ,to the furnace sin order 1136 promote: its solu tion and to :prevenwchillingof th'ezbath; Inany event, from 12.0 to 60 minutes tare usually required to imakezchrom-ium additions itbithe b-ath-sbec'a'use the fenc -chromium has eliiglilmltingipeintrand goes into the solution vslo'wly: :Moreovenudue" to theif act Jtha't chromium educingti-n its; action recoverylofchromium in the steel,- seen-mine, .at least in part, upon the carbon content thereof, is lowland varieszgenerally -from"70%:to 85%.-

The high meltingg pointraniix low rateroi tionlof ferroechroi'hiumralloys also a-de it impossihleoinrthe "past intake awe-pores able additionsorrem)enrolment;aerxrermwmenmm:

-I have discovered that ierro=chromium alloys comprising generally 5% to 70% chromium, up to7% car-bonpup to silicon and the balance substantially iron-in finely divided particles havinig' azrhauimuin sizeiof about one-half inch ,and coated with a 'wettingag'ent will enter into solutionain imclten i'ronwand steel at a greatly facilitated isolutionfl'rate "and will produce a higher and more economical recovery of the chromium. I have-found anumber of wetting agents which arezsuitable for coating the wferro-"chrome alloy particle's to produce the materialof this inventime. The wetting agents of this invention can consist Jot any, material which will lower thesuriacgewtensionof the molten slag or the metal to which the'ferro chrome isadded. .The preferred. wetting agents-for use in my invention are those which contain available free oxygen such as the alkali-metal nitrates,- c'hlorates, peroxides, chromates, zpermanganates; the organic peroxide compounds such-as urearperoxide, acetic peroxide and benzoyl peroxide. However, other wetting agents maybe successfully used, for example, the allral-i metal salts of .t-h'ezhalogens. I believe that these Wetting agents promote the formation of an oxide mm upon the surface of the ferro alloy which oxide film in turn permits the molten metaltoavetthe exposed surfaces of the ferroalloyiand more readily dissolve it.

I hav ound --that irlhide'r to obtain the maximuni efiectiveness-of my invention the chro rx iiiimecontaining' ferro alloy must be crushed to a relativelyaiinely divided state, i. e.-, below oneha'lizihch landipreierablybelow a maximum particle size of about one=quarter inch. The wet ting agent may; be applied to the ferro-chrome particles in any suitable manner as by spraying or immersing the particles in a water solution of the wettinghaieh't and then removing-the water by evaporation orby spraying or immersing the ferro-alloy particles in the molten Wetti-ng agent. The film of' v'vettingoagent which adheres to the chromium :ferlo-alloy particles may vary in amount and thickness depending upon the results desired, the'wetting. agent used and the partieie size'of theferro-alloy. However, I have 'i'oundthat it is not desirable to have more 5 ofth'e wetting-agent in any "given mixbe'aiise thee I er g" the chromium-containing v y r reou'rse obvious that if' the'fei "(fr-chromium particles as first treated are insuinci'enuv'eoated aicer drying, the amount er wettineerent canoe increased by repeating as wet-nae agent is er -no In order to show the effectiveness of the coated chromium-containing ferro-alloy of this invention several heats were made, some using standard chromium alone and others using the coated not afiected by the additions nor was the inclusion count materially altered. The above examples show that it is possible by the use of the material of this invention to produce chrome material of the present invention. 5 steels in open hearth practice by the addition In Table I here below, a series of heats are of crushed chromium-containing.term-alloys to tabulated using standard high carbon-ferrothe ladle. This improvement, in addition to savchrome additions according to the practice of the ing a large percentage of the chromium added, priorart. cuts the time of the heat in the furnace from TabZe'I Prounds R a al on: 'r t 1 Final on P 1118 .0 I Heat Type 001%.; C lfr oi i ie Ad ed Chroime Chromev Lr ifo Added Reference to the above table will show that the to 40 minutes, over the standard practice in the average loss of chromium in making the above industry. heats using standard high-ferro chromium is While I have b a preferred embodiment about 1 which s in general agreement Wlth and practice of my invention, it will be underaverage practice on this type of steel. stood that it may be otherwise embodied within Several heats were then made in the same the scope of the following claims. manner as those of Table I except that ferro- I claim: chrome-silicon twenty mesh down and eight mesh 1. An addition material for making chromium down coated with a wetting agent were added additions to a bath of molten steel comprising a to the metal in the ladle. Heats'Nos. 1, 2, and 3 mixture of finely divided particles of a high were made by adding ferro-chromium-silicon chromium-containing ferro-alloy coated with a twenty mesh and down coated with sodium niwetting agent not exceeding about 5% of the trate. The analysis of the material was 53.57% mixtur chromium, 1 3% ili on, 54% carbon, 3.8 2. An addition material for making chromium sodium nitrate and the balance substantially iron. 40 additiOnS to a bath of molten steel comprising a Heats 4 and 5 were made by adding ferromixture of particles of a high chromium-conchromium-silicon twenty mesh and down coated taining ferro-alloy having a maximum particle with sodium nitrite. Analysis of the coated prodsize of about one-half inch coated with not exuct was 53.25% chromium, 12.95% silicon, 4.60% ceeding about 5% of .a wetting agent. carbon, 4.24% sodium nitrite and the balance 3. An addition material for making chromium substantially iron. Heat No. 6 was made by additions toa bath of molten steel comprising adding ferro-chromium-silicon eight mesh and a mixture of finely divided particles of a high down coated with sodium chlorate. Analysis of chromiumecontaining ferro-alloy having amaxithe finished product was 56.96% chromium, mum particle size of about one-quarter inch 13.40% silicon, 3.56% carbon, 3.20% sodium coated with not exceeding about 5% of a wetting chlorate and the balance substantially iron. 9 agent. Heats 7 and 8 were made by adding ferro- 4. An addition material for making chromium chrome-silicon eight mesh and down coated with additions to a bath of molten steel comprising sodium nitrate. Analysis of the coated product a mixture of finely divided particles of a high was 56.12% chromium, 13.45% silicon, 3.87% chromium-containing ferro-alloy coated with not carbon, 2.66% sodium nitrate. exceeding about 5% of a wettingagent capable Table II PdR'dl Ch 1 11151011: P Type 501.? 05.5: 1.0.0 50.0... 0. 51.. 5.10 2:20

The average loss of chrome is about 2.76% of promoting the formation of an oxide film on which is approximately a saving of about 16.5% the particle surface. chromium over the standard practice illustrated 5. An addition material for making chromium in Table I, thus showing the efiectiveness of the wetting agent in increasing the recovery of chromium. These heats passed all tests for segregation of chromium and were satisfactory additions to a bath of molten steel comprising a mixture of particles of a high chromium-containing ferro-alloy having a maximum particle size of about one-half inch coated with not ex- 111 every respect. Grain size of the steels was 15 ceedingabout 5% of a wetting agent capable of promoting the formation of an oxide film on the particle surface.

6. An addition material for making chromium additions to a bath of molten steel comprising a mixture of finely divided particles of a high chromium-containing ferro-alloy having a maximum particle size of about one-quarter inch coated with not exceeding about 5% of a wetting agent capable of promoting the formation of an oxide film on the particle surface.

7. An addition material for making chromium additions to a bath of molten steel comprising a mixture of finely divided particles of a high chromium-containing ferro-alloy coated with not exceeding about 5% of a wetting agent of the group consisting of alkali nitrates, nitrites, chlorates, peroxides, chromates, permanganates, the organic peroxide compounds and alkali-metal salts of the halogens.

8.. An addition material for making chromium additions to a bath of molten steel comprising a mixture of particles of a high chromium-containing ferro-alloy having a maximum particle size of about one-half inch coated with not exceeding about 5% of a wetting agent of the group consisting of alkali nitrates, nitrites, chlorates, peroxides, chromates, permanganates, organic peroxide compounds and alkali-metal salts of the halogens.

9. An addition material for making chromium additions to a bath of molten steel comprising a mixture of finely divided particles of a high chromium-containing ferro-alloy having a maximum particle size of about one-quarter inch coated with not exceeding about 5% of a wetting agent of the group consisting of alkali nitrates, nitrites, chlorates, peroxides, chromates, permanganates, the organic peroxide compounds and alkali-metal salts of the halogens.

10. An addition material for making chromium additions to a bath of molten steel comprising a mixture of particles of ferro-alloy comprising 5% to 70% chromium, up to 7% carbon, up to 50% silicon and the balance substantially iron, said particles being coated. with not exceeding about 5% of a wetting agent.

11. An addition material for making chromium additions to a bath of molten steel comprising a mixture of particles of ferro-alloy comprising 5% to 70 chromium, up to 7% carbon,

6 up to silicon and the balance substantially iron, said particles being coated with not exceeding about 5% of a wetting agent of the group consisting of alkali nitrate, nitrites, chlorates, peroxides, chromates, permanganates, the organic peroxide compounds and alkali-metal salts of the halogens.

12. The method of adding chromium to molten iron and steel which comprises coating finely divided particles of a high chromium-containing ferro-alloy with a film of wetting agent which will permit the chromium ferro-alloy to be wetted by the molten metal and adding the coated finely divided particles of high chromium-containing ferro-alloy to the molten metal whereby the particles of ferro-alloy are substantially immediately wetted by the molten metal and go into solution therein.

13. The method of adding chromium to molten iron and steel which comprises coating particles of a high chromium-containing ferro-alloy having a maximum particle size, of about one-half inch with a film of wetting agent which will permit the chromium ferro-alloy to be wetted by the molten metal, said wetting agent making up not more than 5% of the resulting composition and adding the coated particles of ferro-alloy to the molten metal whereby the particles of ferro-alloy are substantially immediately wetted by the molten metal and enter into the solution therein.

14. The method of adding chromium to molten iron and steel which comprises coating particles of a high chromium-containing ferroalloy whose maximum particle size is about onehalf inch with a film of wetting agent of the group consisting of alkali nitrates, nitrites, chlorates, peroxides, chromates, permanganates, the organic peroxide compounds and alkali salts of the halogens and adding coated particles of ferro-alloy to the molten metal whereby they are substantially immediately wetted by the molten metal and enter into the solution therein.

JAMES C. VIGNO-S.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 1,529,669 Petinot Mar. 17, 1925 2,496,074 Vignos Jan. 31, 1950 

1. AN ADDITION MATERIAL FOR MAKING CHROMIUM ADDITIONS TO A BATH OF MOLTEN STEEL COMPRISING A MIXTURE OF FINELY DIVIDED PARTICLES OF A HIGH CHROMIUM-CONTAINING FERRO-ALLOY COATED WITH A WETTING AGENT NOT EXCEEDING ABOUT 5% OF THE MIXTURE. 